Absorbent material including coir fibres and/or coir dust

ABSTRACT

PCT No. PCT/AU97/00535 Sec. 371 Date May 24, 1999 Sec. 102(e) Date May 24, 1999 PCT Filed Aug. 21, 1997 PCT Pub. No. WO98/07804 PCT Pub. Date Feb. 26, 1998A fire retardant absorbent material including coir fibres and/or coir dust, an effective quantity of a fire retardant material in the form of small particles, the particle size of the fire retardant material being of the order of less than 1 micron to ensure that the fire retardant material substantially penetrates or substantially coats at least a substantial proportion of the coir fibres present in the absorbent material.

FIELD OF THE INVENTION

This invention relates to absorbent materials.

BACKGROUND OF THE INVENTION

The use of coir dust as an absorber of spills of various types has beenknown for some time, although not widely used. In U.S Pat. No.3,703,464, the use of coir dust or coconut short fibers is described asa satisfactory absorbent material for oil spills on water and on othersurfaces. The widespread use of this material as a spill absorbent hasbeen restricted to situations where exposure to high levels of heat orfire are not present since coir dust is capable of burning and istherefore regarded as a potential fire hazard.

SUMMARY OF INVENTION AND OBJECT

It is the object of the present invention to provide an improvedabsorbent material which can be used in situations involving high levelsof heat or fire.

The invention therefore provides an absorbent material including coirfibers and/or coir dust, an effective quantity of a fire retardantmaterial in the form of small particles, the particle size of the fireretardant material being selected to ensure that the fire retardantmaterial substantially penetrates or substantially coats at least asubstantial proportion of the coir fibers present in the absorbentmaterial.

Preferably, the fire retardant is in the form of a powder, the particlesize of which is smaller than the particle size of the coir fibersand/or coir dust to encore that the fire retardant materialsubstantially penetrates the coir fibers present in the absorbentmaterial.

The fire retardant may include a suitable phosphate material, such asammonium polyphosphate. In its most preferred form, the fire retardantmaterial comprises superphosphate. The inventors have found thatsuperphosphate functions adequately as a fire retardant and that theabove defined combination of coir fibers and/or coir dust andsuperphosphate in the form of a powdered results in an absorbentmaterial which is essentially self-extinguishing in the presence of highlevels of heat or fire.

It has been found that superphosphate in fine powder form, similar totalcum powder, and preferably having a particle size less than 10microns, and preferably less than 5 microns and most preferably of theorder of one micron performs satisfactorily in that it adequatelypenetrates the coconut fibers present in the absorbent material toprovide a self-extinguishing property in these fibers.

In a preferred form, the absorbent material includes from about 4 to atleast about 8 grams of powdered superphosphate to 115 grams or 1 literof dry coir dust, together with sufficient water or other suitableliquid to ensure intimate mixing.

In another aspect, the invention provides a method of producing anabsorbent material including intimately mixing coir fibers and/or coirdust with an effective quantity of a fire retardant material in the formof small particles, and adding an effective quantity of a liquid such aswater to promote intimate mixing of the coir fibers and the fireretardant material whereby the fire retardant penetrates or coats thecoir fibers, the particle size of the fire retardant material beingselected to ensure that the fire retardant penetrates or coats the coirfibers in the absorbent material.

Preferably, the fire retardant is in the form of a powder, the particlesize of which is smaller than the particle size of the coir fibersand/or coir dust to ensure that the fire retardant materialsubstantially penetrates the coir fibers present in the absorbentmaterial.

In a preferred form of the method, powdered superphosphate is used asthe fire retardant. It has been found that satisfactory results areachieved by the following mixtures: from about 4 grams to at least about8 grams of powdered superphosphate to 115 grams or 1 liter of dry coirdust and approximately 65 mL water intimately mixed together to ensurepenetration of the powdered superphosphate into the coir fibers.

An inspection of the absorbent material according to the abovecombination shows evidence of small crystals of superphosphate embeddedin the walls of the coir fiber nodules. These crystals are believed tocontain water of crystallisation which is released when the absorbentmaterial is heated thereby producing the desired self-extinguishingproperties.

DESCRIPTION OF PREFERRED EMBODIMENT

Coir dust in the form of compressed bricks 200 mm×100 mm×50 mm arereconstituted as coir dust and then intimately mixed with superphosphateand water in the ratio about 115 grams or 1 liter of dry coir dust toabout 8 grams superphosphate to about 65 mL of water. To ensure properreconstitution of the bricks and intimate mixing of the resultant coirdust, the coir dust bricks are placed in a rotating hammer mill and afine mist of water is sprayed onto the bricks as they are converted tothe constituent coir dust by the hammer mill. At the same time,superphosphate in the form of a fine powder having a particle size ofthe order of 1 micron is added to the mill.

A typical analysis of the absorbent product described above is asfollows:

    ______________________________________                                        Nitrogen (N) as Protein                                                                           0.52%                                                       Phosphorus (P) as Phosphate 0.57%                                             Potassium (K) 0.19%                                                           Calcium (Ca)  1.2%                                                            Sulphur (S) as Sulphate 0.72%                                                 pH of water extract  5.6                                                    ______________________________________                                    

As mentioned above, a microscopic inspection of the coir fiber nodulescontained in the coir dust shows evidence of small crystals ofsuperphosphate embedded in the walls of the nodules. These crystals arebelieved to contain water of crystallization which is released when theabsorbent material is heated thereby aiding in fire retardation.

Acceptable results are achieved using as little as about 4 grams ofpowdered superphosphate to 115 grams or 1 liter of dry coir dust andabout 65 mL of water. Better results are achieved using 6 grams ofpowdered superphosphate and best results are achieved using 8 grams ofsuperphosphate. The use of more than 8 grams of superphosphate does notseem to improve performance to any material extent.

The absorbent material is relatively inert and of low toxicity and isbiodegradable. Where the product is used to absorb oil spills, theabsorbed oil may burn if exposed to sufficient heat or flame, but thisburning can be controlled by spreading further absorbent product overthe fire.

What is claimed is:
 1. An absorbent material including coir fibersand/or coir dust, a phosphate containing fire retardant material in theform of small particles, the particle size of the fire retardantmaterial being smaller than the particle size of the coir fibers and/ordust to ensure that the fire retardant material penetrates or coats atleast a portion of the coir fibers present in the absorbent material. 2.The absorbent material of claim 1, wherein the powder has a particlesize of the order of less than 10 microns.
 3. The absorbent material ofclaim 2, wherein the powder has a particle size of the order of lessthan 5 microns.
 4. The absorbent material of claim 3, wherein the powderhas a particle size of the order of less than 1 micron to enablepenetration of the coir fibers in the absorbent material.
 5. Theabsorbent material of claim 1 wherein the phosphate material is anammonium polyphosphate.
 6. The absorbent material of claim 5, whereinthe phosphate material is superphosphate.
 7. The absorbent material ofclaim 6, including from about 4 to at least about 8 grams of powderedsuperphosphate to about 115 grams or 1 liter of dry coir dust, togetherwith about 65 ml of water to ensure intimate mixing.
 8. A method ofproducing an absorbent material including intimately mixing coir fibersand/or coir dust with fire retardant quantity of a phosphate containingfire retardant material in the form of small particles having a particlesize smaller than the particle size of the coir fibers and/or coir dust,and adding water to promote intimate mixing of the coir fibers and thefire retardant material whereby the fire retardant penetrates or coatsthe coir fibers.
 9. The method of claim 8, wherein the powder has aparticle size of the order of less than 10 microns.
 10. The method ofclaim 9, wherein the powder has a particle size of the order of lessthan 5 microns.
 11. The method of claim 10, wherein the powder has aparticle size of the order of less than 1 micron.
 12. The method ofclaim 8, wherein the phosphate material is an ammonium polyphosphate.13. The method of claim 12, wherein the phosphate material issuperphosphate.
 14. The method of claim 13, including from about 4 to atleast about 8 grams of powdered superphosphate to 115 grams or 1 literof dry coir dust, together with about 65 ml of water to ensure intimatemixing.
 15. The absorbent material of claim 4, wherein the phosphatematerial is an ammonium polyphosphate.
 16. The method of claim 11,wherein the phosphate material is an ammonium polyphosphate.